2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
6 <refentry id=
"systemd.network" conditional='ENABLE_NETWORKD'
7 xmlns:
xi=
"http://www.w3.org/2001/XInclude">
10 <title>systemd.network
</title>
11 <productname>systemd
</productname>
15 <refentrytitle>systemd.network
</refentrytitle>
16 <manvolnum>5</manvolnum>
20 <refname>systemd.network
</refname>
21 <refpurpose>Network configuration
</refpurpose>
25 <para><filename><replaceable>network
</replaceable>.network
</filename></para>
29 <title>Description
</title>
31 <para>Network setup is performed by
32 <citerefentry><refentrytitle>systemd-networkd
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
35 <para>The main network file must have the extension
<filename>.network
</filename>; other
36 extensions are ignored. Networks are applied to links whenever the links appear.
</para>
38 <para>The
<filename>.network
</filename> files are read from the files located in the system network
39 directories
<filename>/usr/lib/systemd/network
</filename> and
40 <filename>/usr/local/lib/systemd/network
</filename>, the volatile runtime network directory
41 <filename>/run/systemd/network
</filename> and the local administration network directory
42 <filename>/etc/systemd/network
</filename>. All configuration files are collectively sorted and processed
43 in lexical order, regardless of the directories in which they live. However, files with identical
44 filenames replace each other. Files in
<filename>/etc
</filename> have the highest priority, files in
45 <filename>/run
</filename> take precedence over files with the same name under
46 <filename>/usr
</filename>. This can be used to override a system-supplied configuration file with a local
47 file if needed. As a special case, an empty file (file size
0) or symlink with the same name pointing to
48 <filename>/dev/null
</filename> disables the configuration file entirely (it is
"masked").
</para>
50 <para>Along with the network file
<filename>foo.network
</filename>, a
"drop-in" directory
51 <filename>foo.network.d/
</filename> may exist. All files with the suffix
52 <literal>.conf
</literal> from this directory will be parsed after the file itself is
53 parsed. This is useful to alter or add configuration settings, without having to modify the main
54 configuration file. Each drop-in file must have appropriate section headers.
</para>
56 <para>In addition to
<filename>/etc/systemd/network
</filename>, drop-in
<literal>.d
</literal>
57 directories can be placed in
<filename>/usr/lib/systemd/network
</filename> or
58 <filename>/run/systemd/network
</filename> directories. Drop-in files in
59 <filename>/etc
</filename> take precedence over those in
<filename>/run
</filename> which in turn
60 take precedence over those in
<filename>/usr/lib
</filename>. Drop-in files under any of these
61 directories take precedence over the main network file wherever located.
</para>
63 <para>Note that an interface without any static IPv6 addresses configured, and neither DHCPv6
64 nor IPv6LL enabled, shall be considered to have no IPv6 support. IPv6 will be automatically
65 disabled for that interface by writing
"1" to
66 <filename>/proc/sys/net/ipv6/conf/
<replaceable>ifname
</replaceable>/disable_ipv6
</filename>.
71 <title>[Match] Section Options
</title>
73 <para>The network file contains a
<literal>[Match]
</literal>
74 section, which determines if a given network file may be applied
75 to a given device; and a
<literal>[Network]
</literal> section
76 specifying how the device should be configured. The first (in
77 lexical order) of the network files that matches a given device
78 is applied, all later files are ignored, even if they match as
81 <para>A network file is said to match a network interface if all matches specified by the
82 <literal>[Match]
</literal> section are satisfied. When a network file does not contain valid
83 settings in
<literal>[Match]
</literal> section, then the file will match all interfaces and
84 <command>systemd-networkd
</command> warns about that. Hint: to avoid the warning and to make it
85 clear that all interfaces shall be matched, add the following:
86 <programlisting>Name=*
</programlisting>
87 The following keys are accepted:
</para>
89 <variablelist class='network-directives'
>
90 <xi:include href=
"systemd.link.xml" xpointer=
"mac-address" />
91 <xi:include href=
"systemd.link.xml" xpointer=
"permanent-mac-address" />
92 <xi:include href=
"systemd.link.xml" xpointer=
"path" />
93 <xi:include href=
"systemd.link.xml" xpointer=
"driver" />
94 <xi:include href=
"systemd.link.xml" xpointer=
"type" />
95 <xi:include href=
"systemd.link.xml" xpointer=
"property" />
98 <term><varname>Name=
</varname></term>
100 <para>A whitespace-separated list of shell-style globs matching the device name, as exposed
101 by the udev property
<literal>INTERFACE
</literal>, or device's alternative names. If the
102 list is prefixed with a
"!", the test is inverted.
</para>
107 <term><varname>WLANInterfaceType=
</varname></term>
109 <para>A whitespace-separated list of wireless network type. Supported values are
110 <literal>ad-hoc
</literal>,
<literal>station
</literal>,
<literal>ap
</literal>,
111 <literal>ap-vlan
</literal>,
<literal>wds
</literal>,
<literal>monitor
</literal>,
112 <literal>mesh-point
</literal>,
<literal>p2p-client
</literal>,
<literal>p2p-go
</literal>,
113 <literal>p2p-device
</literal>,
<literal>ocb
</literal>, and
<literal>nan
</literal>. If the
114 list is prefixed with a
"!", the test is inverted.
120 <term><varname>SSID=
</varname></term>
122 <para>A whitespace-separated list of shell-style globs matching the SSID of the currently
123 connected wireless LAN. If the list is prefixed with a
"!", the test is inverted.
129 <term><varname>BSSID=
</varname></term>
131 <para>A whitespace-separated list of hardware address of the currently connected wireless
132 LAN. Use full colon-, hyphen- or dot-delimited hexadecimal. See the example in
133 <varname>MACAddress=
</varname>. This option may appear more than one, in which case the
134 lists are merged. If the empty string is assigned to this option, the list of BSSID defined
135 prior to this is reset.
</para>
139 <xi:include href=
"systemd.link.xml" xpointer=
"host" />
140 <xi:include href=
"systemd.link.xml" xpointer=
"virtualization" />
141 <xi:include href=
"systemd.link.xml" xpointer=
"kernel-command-line" />
142 <xi:include href=
"systemd.link.xml" xpointer=
"kernel-version" />
143 <xi:include href=
"systemd.link.xml" xpointer=
"architecture" />
149 <title>[Link] Section Options
</title>
151 <para> The
<literal>[Link]
</literal> section accepts the following keys:
</para>
153 <variablelist class='network-directives'
>
155 <term><varname>MACAddress=
</varname></term>
157 <para>The hardware address to set for the device.
</para>
161 <term><varname>MTUBytes=
</varname></term>
163 <para>The maximum transmission unit in bytes to set for the
164 device. The usual suffixes K, M, G, are supported and are
165 understood to the base of
1024.
</para>
166 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
167 below
1280 (the minimum MTU for IPv6) it will automatically be increased to this value.
</para>
171 <term><varname>ARP=
</varname></term>
173 <para>Takes a boolean. If set to true, the ARP (low-level Address Resolution Protocol)
174 for this interface is enabled. When unset, the kernel's default will be used.
</para>
175 <para> For example, disabling ARP is useful when creating multiple MACVLAN or VLAN virtual
176 interfaces atop a single lower-level physical interface, which will then only serve as a
177 link/
"bridge" device aggregating traffic to the same physical link and not participate in
178 the network otherwise.
</para>
182 <term><varname>Multicast=
</varname></term>
184 <para>Takes a boolean. If set to true, the multicast flag on the device is enabled.
</para>
188 <term><varname>AllMulticast=
</varname></term>
190 <para>Takes a boolean. If set to true, the driver retrieves all multicast packets from the network.
191 This happens when multicast routing is enabled.
</para>
195 <term><varname>Unmanaged=
</varname></term>
197 <para>Takes a boolean. When
<literal>yes
</literal>, no attempts are
198 made to bring up or configure matching links, equivalent to
199 when there are no matching network files. Defaults to
200 <literal>no
</literal>.
</para>
201 <para>This is useful for preventing later matching network
202 files from interfering with certain interfaces that are fully
203 controlled by other applications.
</para>
207 <term><varname>RequiredForOnline=
</varname></term>
209 <para>Takes a boolean or a minimum operational state and an optional maximum operational state.
210 Please see
<citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
211 for possible operational states. When
<literal>yes
</literal>, the network is deemed required when
212 determining whether the system is online when running
213 <command>systemd-networkd-wait-online
</command>. When
<literal>no
</literal>, the network is ignored
214 when checking for online state. When a minimum operational state and an optional maximum operational
215 state are set,
<literal>yes
</literal> is implied, and this controls the minimum and maximum
216 operational state required for the network interface to be considered online.
217 Defaults to
<literal>yes
</literal>.
</para>
219 <para>The network will be brought up normally in all cases, but in
220 the event that there is no address being assigned by DHCP or the
221 cable is not plugged in, the link will simply remain offline and be
222 skipped automatically by
<command>systemd-networkd-wait-online
</command>
223 if
<literal>RequiredForOnline=no
</literal>.
</para>
230 <title>[Network] Section Options
</title>
232 <para>The
<literal>[Network]
</literal> section accepts the following keys:
</para>
234 <variablelist class='network-directives'
>
236 <term><varname>Description=
</varname></term>
238 <para>A description of the device. This is only used for
239 presentation purposes.
</para>
243 <term><varname>DHCP=
</varname></term>
245 <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts
246 <literal>yes
</literal>,
<literal>no
</literal>,
247 <literal>ipv4
</literal>, or
<literal>ipv6
</literal>. Defaults
248 to
<literal>no
</literal>.
</para>
250 <para>Note that DHCPv6 will by default be triggered by Router
251 Advertisement, if that is enabled, regardless of this parameter.
252 By enabling DHCPv6 support explicitly, the DHCPv6 client will
253 be started regardless of the presence of routers on the link,
254 or what flags the routers pass. See
255 <literal>IPv6AcceptRA=
</literal>.
</para>
257 <para>Furthermore, note that by default the domain name
258 specified through DHCP is not used for name resolution.
259 See option
<option>UseDomains=
</option> below.
</para>
261 <para>See the
<literal>[DHCPv4]
</literal> or
<literal>[DHCPv6]
</literal> section below for
262 further configuration options for the DHCP client support.
</para>
266 <term><varname>DHCPServer=
</varname></term>
268 <para>Takes a boolean. If set to
<literal>yes
</literal>, DHCPv4 server will be started. Defaults
269 to
<literal>no
</literal>. Further settings for the DHCP
270 server may be set in the
<literal>[DHCPServer]
</literal>
271 section described below.
</para>
275 <term><varname>LinkLocalAddressing=
</varname></term>
277 <para>Enables link-local address autoconfiguration. Accepts
<literal>yes
</literal>,
278 <literal>no
</literal>,
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
279 <literal>fallback
</literal>, or
<literal>ipv4-fallback
</literal>. If
280 <literal>fallback
</literal> or
<literal>ipv4-fallback
</literal> is specified, then an IPv4
281 link-local address is configured only when DHCPv4 fails. If
<literal>fallback
</literal>,
282 an IPv6 link-local address is always configured, and if
<literal>ipv4-fallback
</literal>,
283 the address is not configured. Note that, the fallback mechanism works only when DHCPv4
284 client is enabled, that is, it requires
<literal>DHCP=yes
</literal> or
285 <literal>DHCP=ipv4
</literal>. If
<varname>Bridge=
</varname> is set, defaults to
286 <literal>no
</literal>, and if not, defaults to
<literal>ipv6
</literal>.
291 <term><varname>IPv4LLRoute=
</varname></term>
293 <para>Takes a boolean. If set to true, sets up the route needed for
294 non-IPv4LL hosts to communicate with IPv4LL-only hosts. Defaults
300 <term><varname>DefaultRouteOnDevice=
</varname></term>
302 <para>Takes a boolean. If set to true, sets up the default route bound to the interface.
303 Defaults to false. This is useful when creating routes on point-to-point interfaces.
304 This is equivalent to e.g. the following.
305 <programlisting>ip route add default dev veth99
</programlisting></para>
309 <term><varname>IPv6Token=
</varname></term>
311 <para>Specifies an optional address generation mechanism and an optional address prefix. If
312 the mechanism is present, the two parts must be separated with a colon
313 <literal><replaceable>type
</replaceable>:
<replaceable>prefix
</replaceable></literal>. The
314 address generation mechanism may be either
<constant>prefixstable
</constant> or
315 <constant>static
</constant>. If not specified,
<constant>static
</constant> is assumed. When
316 set to
<literal>prefixstable
</literal> a method for generating IPv6 Interface Identifiers to
317 be used with IPv6 Stateless Address Autocon figuration (SLAAC). See
318 <ulink url=
"https://tools.ietf.org/html/rfc7217">RFC
7217</ulink>. When IPv6 address is set,
319 indicates the
64-bit interface part of SLAAC IPv6 addresses for this link.
</para>
321 <para>Note that the token is only ever used for SLAAC, and not for DHCPv6 addresses, even in
322 the case DHCP is requested by router advertisement. By default, the token is autogenerated.
327 <term><varname>LLMNR=
</varname></term>
329 <para>Takes a boolean or
<literal>resolve
</literal>. When true,
331 url=
"https://tools.ietf.org/html/rfc4795">Link-Local
332 Multicast Name Resolution
</ulink> on the link. When set to
333 <literal>resolve
</literal>, only resolution is enabled,
334 but not host registration and announcement. Defaults to
335 true. This setting is read by
336 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
340 <term><varname>MulticastDNS=
</varname></term>
342 <para>Takes a boolean or
<literal>resolve
</literal>. When true,
344 url=
"https://tools.ietf.org/html/rfc6762">Multicast
345 DNS
</ulink> support on the link. When set to
346 <literal>resolve
</literal>, only resolution is enabled,
347 but not host or service registration and
348 announcement. Defaults to false. This setting is read by
349 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
353 <term><varname>DNSOverTLS=
</varname></term>
355 <para>Takes a boolean or
<literal>opportunistic
</literal>.
358 url=
"https://tools.ietf.org/html/rfc7858">DNS-over-TLS
</ulink>
360 When set to
<literal>opportunistic
</literal>, compatibility with
361 non-DNS-over-TLS servers is increased, by automatically
362 turning off DNS-over-TLS servers in this case.
363 This option defines a per-interface setting for
364 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
365 global
<varname>DNSOverTLS=
</varname> option. Defaults to
366 false. This setting is read by
367 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
371 <term><varname>DNSSEC=
</varname></term>
373 <para>Takes a boolean. or
374 <literal>allow-downgrade
</literal>. When true, enables
376 url=
"https://tools.ietf.org/html/rfc4033">DNSSEC
</ulink>
377 DNS validation support on the link. When set to
378 <literal>allow-downgrade
</literal>, compatibility with
379 non-DNSSEC capable networks is increased, by automatically
380 turning off DNSSEC in this case. This option defines a
381 per-interface setting for
382 <citerefentry><refentrytitle>resolved.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
383 global
<varname>DNSSEC=
</varname> option. Defaults to
384 false. This setting is read by
385 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
389 <term><varname>DNSSECNegativeTrustAnchors=
</varname></term>
390 <listitem><para>A space-separated list of DNSSEC negative
391 trust anchor domains. If specified and DNSSEC is enabled,
392 look-ups done via the interface's DNS server will be subject
393 to the list of negative trust anchors, and not require
394 authentication for the specified domains, or anything below
395 it. Use this to disable DNSSEC authentication for specific
396 private domains, that cannot be proven valid using the
397 Internet DNS hierarchy. Defaults to the empty list. This
399 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
403 <term><varname>LLDP=
</varname></term>
405 <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol commonly
406 implemented on professional routers and bridges which announces which physical port a system is connected
407 to, as well as other related data. Accepts a boolean or the special value
408 <literal>routers-only
</literal>. When true, incoming LLDP packets are accepted and a database of all LLDP
409 neighbors maintained. If
<literal>routers-only
</literal> is set only LLDP data of various types of routers
410 is collected and LLDP data about other types of devices ignored (such as stations, telephones and
411 others). If false, LLDP reception is disabled. Defaults to
<literal>routers-only
</literal>. Use
412 <citerefentry><refentrytitle>networkctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry> to query the
413 collected neighbor data. LLDP is only available on Ethernet links. See
<varname>EmitLLDP=
</varname> below
414 for enabling LLDP packet emission from the local system.
419 <term><varname>EmitLLDP=
</varname></term>
421 <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the special values
422 <literal>nearest-bridge
</literal>,
<literal>non-tpmr-bridge
</literal> and
423 <literal>customer-bridge
</literal>. Defaults to false, which turns off LLDP packet emission. If not false,
424 a short LLDP packet with information about the local system is sent out in regular intervals on the
425 link. The LLDP packet will contain information about the local host name, the local machine ID (as stored
426 in
<citerefentry><refentrytitle>machine-id
</refentrytitle><manvolnum>5</manvolnum></citerefentry>) and the
427 local interface name, as well as the pretty hostname of the system (as set in
428 <citerefentry><refentrytitle>machine-info
</refentrytitle><manvolnum>5</manvolnum></citerefentry>). LLDP
429 emission is only available on Ethernet links. Note that this setting passes data suitable for
430 identification of host to the network and should thus not be enabled on untrusted networks, where such
431 identification data should not be made available. Use this option to permit other systems to identify on
432 which interfaces they are connected to this system. The three special values control propagation of the
433 LLDP packets. The
<literal>nearest-bridge
</literal> setting permits propagation only to the nearest
434 connected bridge,
<literal>non-tpmr-bridge
</literal> permits propagation across Two-Port MAC Relays, but
435 not any other bridges, and
<literal>customer-bridge
</literal> permits propagation until a customer bridge
436 is reached. For details about these concepts, see
<ulink
437 url=
"https://standards.ieee.org/findstds/standard/802.1AB-2016.html">IEEE
802.1AB-
2016</ulink>. Note that
438 configuring this setting to true is equivalent to
<literal>nearest-bridge
</literal>, the recommended and
439 most restricted level of propagation. See
<varname>LLDP=
</varname> above for an option to enable LLDP
444 <term><varname>BindCarrier=
</varname></term>
446 <para>A link name or a list of link names. When set, controls the behavior of the current
447 link. When all links in the list are in an operational down state, the current link is brought
448 down. When at least one link has carrier, the current interface is brought up.
453 <term><varname>Address=
</varname></term>
455 <para>A static IPv4 or IPv6 address and its prefix length,
456 separated by a
<literal>/
</literal> character. Specify
457 this key more than once to configure several addresses.
458 The format of the address must be as described in
459 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
460 This is a short-hand for an [Address] section only
461 containing an Address key (see below). This option may be
462 specified more than once.
465 <para>If the specified address is
<literal>0.0.0.0</literal> (for IPv4) or
<literal>::
</literal>
466 (for IPv6), a new address range of the requested size is automatically allocated from a
467 system-wide pool of unused ranges. Note that the prefix length must be equal or larger than
8 for
468 IPv4, and
64 for IPv6. The allocated range is checked against all current network interfaces and
469 all known network configuration files to avoid address range conflicts. The default system-wide
470 pool consists of
192.168.0.0/
16,
172.16.0.0/
12 and
10.0.0.0/
8 for IPv4, and fd00::/
8 for IPv6.
471 This functionality is useful to manage a large number of dynamically created network interfaces
472 with the same network configuration and automatic address range assignment.
</para>
477 <term><varname>Gateway=
</varname></term>
479 <para>The gateway address, which must be in the format
481 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
482 This is a short-hand for a [Route] section only containing
483 a Gateway key. This option may be specified more than
488 <term><varname>DNS=
</varname></term>
490 <para>A DNS server address, which must be in the format
492 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
493 This option may be specified more than once. This setting is read by
494 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
498 <term><varname>Domains=
</varname></term>
500 <para>A list of domains which should be resolved using the DNS servers on this link. Each item in the list
501 should be a domain name, optionally prefixed with a tilde (
<literal>~
</literal>). The domains with the
502 prefix are called
"routing-only domains". The domains without the prefix are called
"search domains" and
503 are first used as search suffixes for extending single-label host names (host names containing no dots) to
504 become fully qualified domain names (FQDNs). If a single-label host name is resolved on this interface,
505 each of the specified search domains are appended to it in turn, converting it into a fully qualified
506 domain name, until one of them may be successfully resolved.
</para>
508 <para>Both
"search" and
"routing-only" domains are used for routing of DNS queries: look-ups for host names
509 ending in those domains (hence also single label names, if any
"search domains" are listed), are routed to
510 the DNS servers configured for this interface. The domain routing logic is particularly useful on
511 multi-homed hosts with DNS servers serving particular private DNS zones on each interface.
</para>
513 <para>The
"routing-only" domain
<literal>~.
</literal> (the tilde indicating definition of a routing domain,
514 the dot referring to the DNS root domain which is the implied suffix of all valid DNS names) has special
515 effect. It causes all DNS traffic which does not match another configured domain routing entry to be routed
516 to DNS servers specified for this interface. This setting is useful to prefer a certain set of DNS servers
517 if a link on which they are connected is available.
</para>
519 <para>This setting is read by
520 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
521 "Search domains" correspond to the
<varname>domain
</varname> and
<varname>search
</varname> entries in
522 <citerefentry project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
523 Domain name routing has no equivalent in the traditional glibc API, which has no concept of domain
524 name servers limited to a specific link.
</para>
528 <term><varname>DNSDefaultRoute=
</varname></term>
530 <para>Takes a boolean argument. If true, this link's configured DNS servers are used for resolving domain
531 names that do not match any link's configured
<varname>Domains=
</varname> setting. If false, this link's
532 configured DNS servers are never used for such domains, and are exclusively used for resolving names that
533 match at least one of the domains configured on this link. If not specified defaults to an automatic mode:
534 queries not matching any link's configured domains will be routed to this link if it has no routing-only
535 domains configured.
</para>
539 <term><varname>NTP=
</varname></term>
541 <para>An NTP server address. This option may be specified more than once. This setting is read by
542 <citerefentry><refentrytitle>systemd-timesyncd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
546 <term><varname>IPForward=
</varname></term>
547 <listitem><para>Configures IP packet forwarding for the
548 system. If enabled, incoming packets on any network
549 interface will be forwarded to any other interfaces
550 according to the routing table. Takes a boolean,
551 or the values
<literal>ipv4
</literal> or
552 <literal>ipv6
</literal>, which only enable IP packet
553 forwarding for the specified address family. This controls
554 the
<filename>net.ipv4.ip_forward
</filename> and
555 <filename>net.ipv6.conf.all.forwarding
</filename> sysctl
556 options of the network interface (see
<ulink
557 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink>
558 for details about sysctl options). Defaults to
559 <literal>no
</literal>.
</para>
561 <para>Note: this setting controls a global kernel option,
562 and does so one way only: if a network that has this setting
563 enabled is set up the global setting is turned on. However,
564 it is never turned off again, even after all networks with
565 this setting enabled are shut down again.
</para>
567 <para>To allow IP packet forwarding only between specific
568 network interfaces use a firewall.
</para>
572 <term><varname>IPMasquerade=
</varname></term>
573 <listitem><para>Configures IP masquerading for the network
574 interface. If enabled, packets forwarded from the network
575 interface will be appear as coming from the local host.
576 Takes a boolean argument. Implies
577 <varname>IPForward=ipv4
</varname>. Defaults to
578 <literal>no
</literal>.
</para></listitem>
581 <term><varname>IPv6PrivacyExtensions=
</varname></term>
582 <listitem><para>Configures use of stateless temporary
583 addresses that change over time (see
<ulink
584 url=
"https://tools.ietf.org/html/rfc4941">RFC
4941</ulink>,
585 Privacy Extensions for Stateless Address Autoconfiguration
586 in IPv6). Takes a boolean or the special values
587 <literal>prefer-public
</literal> and
588 <literal>kernel
</literal>. When true, enables the privacy
589 extensions and prefers temporary addresses over public
590 addresses. When
<literal>prefer-public
</literal>, enables the
591 privacy extensions, but prefers public addresses over
592 temporary addresses. When false, the privacy extensions
593 remain disabled. When
<literal>kernel
</literal>, the kernel's
594 default setting will be left in place. Defaults to
595 <literal>no
</literal>.
</para></listitem>
598 <term><varname>IPv6AcceptRA=
</varname></term>
599 <listitem><para>Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support
600 for the interface. If true, RAs are accepted; if false, RAs are ignored, independently of the
601 local forwarding state. When RAs are accepted, they may trigger the start of the DHCPv6
602 client if the relevant flags are set in the RA data, or if no routers are found on the link.
</para>
604 <para>Further settings for the IPv6 RA support may be configured in the
605 <literal>[IPv6AcceptRA]
</literal> section, see below.
</para>
607 <para>Also see
<ulink
608 url=
"https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt
</ulink> in the kernel
609 documentation regarding
<literal>accept_ra
</literal>, but note that systemd's setting of
610 <constant>1</constant> (i.e. true) corresponds to kernel's setting of
<constant>2</constant>.
</para>
612 <para>Note that kernel's implementation of the IPv6 RA protocol is always disabled,
613 regardless of this setting. If this option is enabled, a userspace implementation of the IPv6
614 RA protocol is used, and the kernel's own implementation remains disabled, since
615 <command>systemd-networkd
</command> needs to know all details supplied in the advertisements,
616 and these are not available from the kernel if the kernel's own implementation is used.
</para>
620 <term><varname>IPv6DuplicateAddressDetection=
</varname></term>
621 <listitem><para>Configures the amount of IPv6 Duplicate
622 Address Detection (DAD) probes to send. When unset, the kernel's default will be used.
626 <term><varname>IPv6HopLimit=
</varname></term>
627 <listitem><para>Configures IPv6 Hop Limit. For each router that
628 forwards the packet, the hop limit is decremented by
1. When the
629 hop limit field reaches zero, the packet is discarded.
630 When unset, the kernel's default will be used.
634 <term><varname>IPv4ProxyARP=
</varname></term>
635 <listitem><para>Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is the technique in which one host,
636 usually a router, answers ARP requests intended for another machine. By
"faking" its identity,
637 the router accepts responsibility for routing packets to the
"real" destination. (see
<ulink
638 url=
"https://tools.ietf.org/html/rfc1027">RFC
1027</ulink>.
639 When unset, the kernel's default will be used.
643 <term><varname>IPv6ProxyNDP=
</varname></term>
644 <listitem><para>Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor Discovery
645 Protocol) is a technique for IPv6 to allow routing of addresses to a different
646 destination when peers expect them to be present on a certain physical link.
647 In this case a router answers Neighbour Advertisement messages intended for
648 another machine by offering its own MAC address as destination.
649 Unlike proxy ARP for IPv4, it is not enabled globally, but will only send Neighbour
650 Advertisement messages for addresses in the IPv6 neighbor proxy table,
651 which can also be shown by
<command>ip -
6 neighbour show proxy
</command>.
652 systemd-networkd will control the per-interface `proxy_ndp` switch for each configured
653 interface depending on this option.
654 When unset, the kernel's default will be used.
658 <term><varname>IPv6ProxyNDPAddress=
</varname></term>
659 <listitem><para>An IPv6 address, for which Neighbour Advertisement messages will be
660 proxied. This option may be specified more than once. systemd-networkd will add the
661 <option>IPv6ProxyNDPAddress=
</option> entries to the kernel's IPv6 neighbor proxy table.
662 This option implies
<option>IPv6ProxyNDP=yes
</option> but has no effect if
663 <option>IPv6ProxyNDP
</option> has been set to false. When unset, the kernel's default will be used.
667 <term><varname>IPv6PrefixDelegation=
</varname></term>
668 <listitem><para>Whether to enable or disable Router Advertisement sending on a link.
669 Allowed values are
<literal>static
</literal> which distributes prefixes as defined in
670 the
<literal>[IPv6PrefixDelegation]
</literal> and any
<literal>[IPv6Prefix]
</literal>
671 sections,
<literal>dhcpv6
</literal> which requests prefixes using a DHCPv6 client
672 configured for another link and any values configured in the
673 <literal>[IPv6PrefixDelegation]
</literal> section while ignoring all static prefix
674 configuration sections,
<literal>yes
</literal> which uses both static configuration
675 and DHCPv6, and
<literal>false
</literal> which turns off IPv6 prefix delegation
676 altogether. Defaults to
<literal>false
</literal>. See the
677 <literal>[IPv6PrefixDelegation]
</literal> and the
<literal>[IPv6Prefix]
</literal>
678 sections for more configuration options.
682 <term><varname>IPv6MTUBytes=
</varname></term>
683 <listitem><para>Configures IPv6 maximum transmission unit (MTU).
684 An integer greater than or equal to
1280 bytes. When unset, the kernel's default will be used.
688 <term><varname>Bridge=
</varname></term>
690 <para>The name of the bridge to add the link to. See
691 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
696 <term><varname>Bond=
</varname></term>
698 <para>The name of the bond to add the link to. See
699 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
704 <term><varname>VRF=
</varname></term>
706 <para>The name of the VRF to add the link to. See
707 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
712 <term><varname>VLAN=
</varname></term>
714 <para>The name of a VLAN to create on the link. See
715 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
716 This option may be specified more than once.
</para>
720 <term><varname>IPVLAN=
</varname></term>
722 <para>The name of a IPVLAN to create on the link. See
723 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
724 This option may be specified more than once.
</para>
728 <term><varname>MACVLAN=
</varname></term>
730 <para>The name of a MACVLAN to create on the link. See
731 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
732 This option may be specified more than once.
</para>
736 <term><varname>VXLAN=
</varname></term>
738 <para>The name of a VXLAN to create on the link. See
739 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
740 This option may be specified more than once.
</para>
744 <term><varname>Tunnel=
</varname></term>
746 <para>The name of a Tunnel to create on the link. See
747 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
748 This option may be specified more than once.
</para>
752 <term><varname>MACsec=
</varname></term>
754 <para>The name of a MACsec device to create on the link. See
755 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
756 This option may be specified more than once.
</para>
760 <term><varname>ActiveSlave=
</varname></term>
762 <para>Takes a boolean. Specifies the new active slave. The
<literal>ActiveSlave=
</literal>
763 option is only valid for following modes:
764 <literal>active-backup
</literal>,
765 <literal>balance-alb
</literal> and
766 <literal>balance-tlb
</literal>. Defaults to false.
771 <term><varname>PrimarySlave=
</varname></term>
773 <para>Takes a boolean. Specifies which slave is the primary device. The specified
774 device will always be the active slave while it is available. Only when the
775 primary is off-line will alternate devices be used. This is useful when
776 one slave is preferred over another, e.g. when one slave has higher throughput
777 than another. The
<literal>PrimarySlave=
</literal> option is only valid for
779 <literal>active-backup
</literal>,
780 <literal>balance-alb
</literal> and
781 <literal>balance-tlb
</literal>. Defaults to false.
786 <term><varname>ConfigureWithoutCarrier=
</varname></term>
788 <para>Takes a boolean. Allows networkd to configure a specific link even if it has no carrier.
794 <term><varname>IgnoreCarrierLoss=
</varname></term>
796 <para>A boolean. Allows networkd to retain both the static and dynamic configuration of the
797 interface even if its carrier is lost. Defaults to false.
802 <term><varname>Xfrm=
</varname></term>
804 <para>The name of the xfrm to create on the link. See
805 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
806 This option may be specified more than once.
</para>
810 <term><varname>KeepConfiguration=
</varname></term>
812 <para>Takes a boolean or one of
<literal>static
</literal>,
<literal>dhcp-on-stop
</literal>,
813 <literal>dhcp
</literal>. When
<literal>static
</literal>,
<command>systemd-networkd
</command>
814 will not drop static addresses and routes on starting up process. When set to
815 <literal>dhcp-on-stop
</literal>,
<command>systemd-networkd
</command> will not drop addresses
816 and routes on stopping the daemon. When
<literal>dhcp
</literal>,
817 the addresses and routes provided by a DHCP server will never be dropped even if the DHCP
818 lease expires. This is contrary to the DHCP specification, but may be the best choice if,
819 e.g., the root filesystem relies on this connection. The setting
<literal>dhcp
</literal>
820 implies
<literal>dhcp-on-stop
</literal>, and
<literal>yes
</literal> implies
821 <literal>dhcp
</literal> and
<literal>static
</literal>. Defaults to
<literal>no
</literal>.
831 <title>[Address] Section Options
</title>
833 <para>An
<literal>[Address]
</literal> section accepts the
834 following keys. Specify several
<literal>[Address]
</literal>
835 sections to configure several addresses.
</para>
837 <variablelist class='network-directives'
>
839 <term><varname>Address=
</varname></term>
841 <para>As in the
<literal>[Network]
</literal> section. This key is mandatory. Each
842 <literal>[Address]
</literal> section can contain one
<varname>Address=
</varname> setting.
</para>
846 <term><varname>Peer=
</varname></term>
848 <para>The peer address in a point-to-point connection.
849 Accepts the same format as the
<varname>Address=
</varname>
854 <term><varname>Broadcast=
</varname></term>
856 <para>The broadcast address, which must be in the format
858 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
859 This key only applies to IPv4 addresses. If it is not
860 given, it is derived from the
<varname>Address=
</varname>
865 <term><varname>Label=
</varname></term>
867 <para>An address label.
</para>
871 <term><varname>PreferredLifetime=
</varname></term>
873 <para>Allows the default
"preferred lifetime" of the address to be overridden.
874 Only three settings are accepted:
<literal>forever
</literal> or
<literal>infinity
</literal>
875 which is the default and means that the address never expires, and
<literal>0</literal> which means
876 that the address is considered immediately
"expired" and will not be used,
877 unless explicitly requested. A setting of PreferredLifetime=
0 is useful for
878 addresses which are added to be used only by a specific application,
879 which is then configured to use them explicitly.
</para>
883 <term><varname>Scope=
</varname></term>
885 <para>The scope of the address, which can be
<literal>global
</literal>,
886 <literal>link
</literal> or
<literal>host
</literal> or an unsigned integer ranges
0 to
255.
887 Defaults to
<literal>global
</literal>.
</para>
891 <term><varname>HomeAddress=
</varname></term>
893 <para>Takes a boolean. Designates this address the
"home address" as defined in
894 <ulink url=
"https://tools.ietf.org/html/rfc6275">RFC
6275</ulink>.
895 Supported only on IPv6. Defaults to false.
</para>
899 <term><varname>DuplicateAddressDetection=
</varname></term>
901 <para>Takes one of
<literal>ipv4
</literal>,
<literal>ipv6
</literal>,
902 <literal>both
</literal>,
<literal>none
</literal>. When
<literal>ipv4
</literal>,
903 performs IPv4 Duplicate Address Detection. See
904 <ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5224</ulink>.
905 When
<literal>ipv6
</literal>, performs IPv6 Duplicate Address Detection. See
906 <ulink url=
"https://tools.ietf.org/html/rfc4862">RFC
4862</ulink>.
907 Defaults to
<literal>ipv6
</literal>.
</para>
911 <term><varname>ManageTemporaryAddress=
</varname></term>
913 <para>Takes a boolean. If true the kernel manage temporary addresses created
914 from this one as template on behalf of Privacy Extensions
915 <ulink url=
"https://tools.ietf.org/html/rfc3041">RFC
3041</ulink>. For this to become
916 active, the use_tempaddr sysctl setting has to be set to a value greater than zero.
917 The given address needs to have a prefix length of
64. This flag allows using privacy
918 extensions in a manually configured network, just like if stateless auto-configuration
919 was active. Defaults to false.
</para>
923 <term><varname>AddPrefixRoute=
</varname></term>
925 <para>Takes a boolean. When true, the prefix route for the address is automatically added.
926 Defaults to true.
</para>
930 <term><varname>AutoJoin=
</varname></term>
932 <para>Takes a boolean. Joining multicast group on ethernet level via
933 <command>ip maddr
</command> command would not work if we have an Ethernet switch that does
934 IGMP snooping since the switch would not replicate multicast packets on ports that did not
935 have IGMP reports for the multicast addresses. Linux vxlan interfaces created via
936 <command>ip link add vxlan
</command> or networkd's netdev kind vxlan have the group option
937 that enables then to do the required join. By extending ip address command with option
938 <literal>autojoin
</literal> we can get similar functionality for openvswitch (OVS) vxlan
939 interfaces as well as other tunneling mechanisms that need to receive multicast traffic.
940 Defaults to
<literal>no
</literal>.
</para>
947 <title>[Neighbor] Section Options
</title>
948 <para>A
<literal>[Neighbor]
</literal> section accepts the
949 following keys. The neighbor section adds a permanent, static
950 entry to the neighbor table (IPv6) or ARP table (IPv4) for
951 the given hardware address on the links matched for the network.
952 Specify several
<literal>[Neighbor]
</literal> sections to configure
953 several static neighbors.
</para>
955 <variablelist class='network-directives'
>
957 <term><varname>Address=
</varname></term>
959 <para>The IP address of the neighbor.
</para>
963 <term><varname>LinkLayerAddress=
</varname></term>
965 <para>The link layer address (MAC address or IP address) of the neighbor.
</para>
972 <title>[IPv6AddressLabel] Section Options
</title>
974 <para>An
<literal>[IPv6AddressLabel]
</literal> section accepts the
975 following keys. Specify several
<literal>[IPv6AddressLabel]
</literal>
976 sections to configure several address labels. IPv6 address labels are
977 used for address selection. See
<ulink url=
"https://tools.ietf.org/html/rfc3484">RFC
3484</ulink>.
978 Precedence is managed by userspace, and only the label itself is stored in the kernel
</para>
980 <variablelist class='network-directives'
>
982 <term><varname>Label=
</varname></term>
984 <para> The label for the prefix (an unsigned integer) ranges
0 to
4294967294.
985 0xffffffff is reserved. This key is mandatory.
</para>
989 <term><varname>Prefix=
</varname></term>
991 <para>IPv6 prefix is an address with a prefix length, separated by a slash
<literal>/
</literal> character.
992 This key is mandatory.
</para>
999 <title>[RoutingPolicyRule] Section Options
</title>
1001 <para>An
<literal>[RoutingPolicyRule]
</literal> section accepts the
1002 following keys. Specify several
<literal>[RoutingPolicyRule]
</literal>
1003 sections to configure several rules.
</para>
1005 <variablelist class='network-directives'
>
1007 <term><varname>TypeOfService=
</varname></term>
1009 <para>Specifies the type of service to match a number between
0 to
255.
</para>
1013 <term><varname>From=
</varname></term>
1015 <para>Specifies the source address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1019 <term><varname>To=
</varname></term>
1021 <para>Specifies the destination address prefix to match. Possibly followed by a slash and the prefix length.
</para>
1025 <term><varname>FirewallMark=
</varname></term>
1027 <para>Specifies the iptables firewall mark value to match (a number between
1 and
4294967295).
</para>
1031 <term><varname>Table=
</varname></term>
1033 <para>Specifies the routing table identifier to lookup if the rule selector matches. Takes
1034 one of
<literal>default
</literal>,
<literal>main
</literal>, and
<literal>local
</literal>,
1035 or a number between
1 and
4294967295. Defaults to
<literal>main
</literal>.
</para>
1039 <term><varname>Priority=
</varname></term>
1041 <para>Specifies the priority of this rule.
<varname>Priority=
</varname> is an unsigned
1042 integer. Higher number means lower priority, and rules get processed in order of increasing number.
</para>
1046 <term><varname>IncomingInterface=
</varname></term>
1048 <para>Specifies incoming device to match. If the interface is loopback, the rule only matches packets originating from this host.
</para>
1052 <term><varname>OutgoingInterface=
</varname></term>
1054 <para>Specifies the outgoing device to match. The outgoing interface is only available for packets originating from local sockets that are bound to a device.
</para>
1058 <term><varname>SourcePort=
</varname></term>
1060 <para>Specifies the source IP port or IP port range match in forwarding information base (FIB) rules.
1061 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1065 <term><varname>DestinationPort=
</varname></term>
1067 <para>Specifies the destination IP port or IP port range match in forwarding information base (FIB) rules.
1068 A port range is specified by the lower and upper port separated by a dash. Defaults to unset.
</para>
1072 <term><varname>IPProtocol=
</varname></term>
1074 <para>Specifies the IP protocol to match in forwarding information base (FIB) rules. Takes IP protocol name such as
<literal>tcp
</literal>,
1075 <literal>udp
</literal> or
<literal>sctp
</literal>, or IP protocol number such as
<literal>6</literal> for
<literal>tcp
</literal> or
1076 <literal>17</literal> for
<literal>udp
</literal>.
1077 Defaults to unset.
</para>
1081 <term><varname>InvertRule=
</varname></term>
1083 <para>A boolean. Specifies whether the rule is to be inverted. Defaults to false.
</para>
1087 <term><varname>Family=
</varname></term>
1089 <para>Takes a special value
<literal>ipv4
</literal>,
<literal>ipv6
</literal>, or
1090 <literal>both
</literal>. By default, the address family is determined by the address
1091 specified in
<varname>To=
</varname> or
<varname>From=
</varname>. If neither
1092 <varname>To=
</varname> nor
<varname>From=
</varname> are specified, then defaults to
1093 <literal>ipv4
</literal>.
</para>
1097 <term><varname>User=
</varname></term>
1099 <para>Takes a username, a user ID, or a range of user IDs separated by a dash. Defaults to
1104 <term><varname>SuppressPrefixLength=
</varname></term>
1106 <para>Takes a number
<replaceable>N
</replaceable> in the range
0-
128 and rejects routing
1107 decisions that have a prefix length of
<replaceable>N
</replaceable> or less. Defaults to
1115 <title>[NextHop] Section Options
</title>
1116 <para>The
<literal>[NextHop]
</literal> section accepts the
1117 following keys. Specify several
<literal>[NextHop]
</literal>
1118 sections to configure several nexthop. Nexthop is used to manipulate entries in the kernel's nexthop
1121 <variablelist class='network-directives'
>
1123 <term><varname>Gateway=
</varname></term>
1125 <para>As in the
<literal>[Network]
</literal> section. This is mandatory.
</para>
1129 <term><varname>Id=
</varname></term>
1131 <para>The id of the nexthop (an unsigned integer). If unspecified or '
0' then automatically chosen by kernel.
</para>
1138 <title>[Route] Section Options
</title>
1139 <para>The
<literal>[Route]
</literal> section accepts the
1140 following keys. Specify several
<literal>[Route]
</literal>
1141 sections to configure several routes.
</para>
1143 <variablelist class='network-directives'
>
1145 <term><varname>Gateway=
</varname></term>
1147 <para>Takes the gateway address or special value
<literal>_dhcp
</literal>. If
1148 <literal>_dhcp
</literal>, then the gateway address provided by DHCP (or in the IPv6 case,
1149 provided by IPv6 RA) is used.
</para>
1153 <term><varname>GatewayOnLink=
</varname></term>
1155 <para>Takes a boolean. If set to true, the kernel does not have
1156 to check if the gateway is reachable directly by the current machine (i.e., the kernel does
1157 not need to check if the gateway is attached to the local network), so that we can insert the
1158 route in the kernel table without it being complained about. Defaults to
<literal>no
</literal>.
1163 <term><varname>Destination=
</varname></term>
1165 <para>The destination prefix of the route. Possibly
1166 followed by a slash and the prefix length. If omitted, a
1167 full-length host route is assumed.
</para>
1171 <term><varname>Source=
</varname></term>
1173 <para>The source prefix of the route. Possibly followed by
1174 a slash and the prefix length. If omitted, a full-length
1175 host route is assumed.
</para>
1179 <term><varname>Metric=
</varname></term>
1181 <para>The metric of the route (an unsigned integer).
</para>
1185 <term><varname>IPv6Preference=
</varname></term>
1187 <para>Specifies the route preference as defined in
<ulink
1188 url=
"https://tools.ietf.org/html/rfc4191">RFC4191
</ulink> for Router Discovery messages.
1189 Which can be one of
<literal>low
</literal> the route has a lowest priority,
1190 <literal>medium
</literal> the route has a default priority or
1191 <literal>high
</literal> the route has a highest priority.
</para>
1195 <term><varname>Scope=
</varname></term>
1197 <para>The scope of the route, which can be
<literal>global
</literal>,
<literal>site
</literal>,
1198 <literal>link
</literal>,
<literal>host
</literal>, or
<literal>nowhere
</literal>. For IPv4 route,
1199 defaults to
<literal>host
</literal> if
<varname>Type=
</varname> is
<literal>local
</literal>
1200 or
<literal>nat
</literal>, and
<literal>link
</literal> if
<varname>Type=
</varname> is
1201 <literal>broadcast
</literal>,
<literal>multicast
</literal>, or
<literal>anycast
</literal>.
1202 In other cases, defaults to
<literal>global
</literal>.
</para>
1206 <term><varname>PreferredSource=
</varname></term>
1208 <para>The preferred source address of the route. The address
1209 must be in the format described in
1210 <citerefentry project='man-pages'
><refentrytitle>inet_pton
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
1214 <term><varname>Table=
</varname></term>
1216 <para>The table identifier for the route. Takes
<literal>default
</literal>,
1217 <literal>main
</literal>,
<literal>local
</literal> or a number between
1 and
4294967295.
1218 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1219 If unset and
<varname>Type=
</varname> is
<literal>local
</literal>,
<literal>broadcast
</literal>,
1220 <literal>anycast
</literal>, or
<literal>nat
</literal>, then
<literal>local
</literal> is used.
1221 In other cases, defaults to
<literal>main
</literal>.
1226 <term><varname>Protocol=
</varname></term>
1228 <para>The protocol identifier for the route. Takes a number between
0 and
255 or the special values
1229 <literal>kernel
</literal>,
<literal>boot
</literal>,
<literal>static
</literal>,
1230 <literal>ra
</literal> and
<literal>dhcp
</literal>. Defaults to
<literal>static
</literal>.
1235 <term><varname>Type=
</varname></term>
1237 <para>Specifies the type for the route. Takes one of
<literal>unicast
</literal>,
1238 <literal>local
</literal>,
<literal>broadcast
</literal>,
<literal>anycast
</literal>,
1239 <literal>multicast
</literal>,
<literal>blackhole
</literal>,
<literal>unreachable
</literal>,
1240 <literal>prohibit
</literal>,
<literal>throw
</literal>,
<literal>nat
</literal>, and
1241 <literal>xresolve
</literal>. If
<literal>unicast
</literal>, a regular route is defined, i.e. a
1242 route indicating the path to take to a destination network address. If
<literal>blackhole
</literal>, packets
1243 to the defined route are discarded silently. If
<literal>unreachable
</literal>, packets to the defined route
1244 are discarded and the ICMP message
"Host Unreachable" is generated. If
<literal>prohibit
</literal>, packets
1245 to the defined route are discarded and the ICMP message
"Communication Administratively Prohibited" is
1246 generated. If
<literal>throw
</literal>, route lookup in the current routing table will fail and the route
1247 selection process will return to Routing Policy Database (RPDB). Defaults to
<literal>unicast
</literal>.
1252 <term><varname>InitialCongestionWindow=
</varname></term>
1254 <para>The TCP initial congestion window is used during the start of a TCP connection. During the start of a TCP
1255 session, when a client requests a resource, the server's initial congestion window determines how many data bytes
1256 will be sent during the initial burst of data. Takes a size in bytes between
1 and
4294967295 (
2^
32 -
1). The usual
1257 suffixes K, M, G are supported and are understood to the base of
1024. When unset, the kernel's default will be used.
1262 <term><varname>InitialAdvertisedReceiveWindow=
</varname></term>
1264 <para>The TCP initial advertised receive window is the amount of receive data (in bytes) that can initially be buffered at one time
1265 on a connection. The sending host can send only that amount of data before waiting for an acknowledgment and window update
1266 from the receiving host. Takes a size in bytes between
1 and
4294967295 (
2^
32 -
1). The usual suffixes K, M, G are supported
1267 and are understood to the base of
1024. When unset, the kernel's default will be used.
1272 <term><varname>QuickAck=
</varname></term>
1274 <para>Takes a boolean. When true enables TCP quick ack mode for the route. When unset, the kernel's default will be used.
1279 <term><varname>FastOpenNoCookie=
</varname></term>
1281 <para>Takes a boolean. When true enables TCP fastopen without a cookie on a per-route basis.
1282 When unset, the kernel's default will be used.
1287 <term><varname>TTLPropagate=
</varname></term>
1289 <para>Takes a boolean. When true enables TTL propagation at Label Switched Path (LSP) egress.
1290 When unset, the kernel's default will be used.
1295 <term><varname>MTUBytes=
</varname></term>
1297 <para>The maximum transmission unit in bytes to set for the
1298 route. The usual suffixes K, M, G, are supported and are
1299 understood to the base of
1024.
</para>
1300 <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen
1301 below
1280 (the minimum MTU for IPv6) it will automatically be increased to this value.
</para>
1305 <term><varname>IPServiceType=
</varname></term>
1307 <para>Takes string;
<literal>CS6
</literal> or
<literal>CS4
</literal>. Used to set IP
1308 service type to CS6 (network control) or CS4 (Realtime). Defaults to CS6.
</para>
1312 <term><varname>MultiPathRoute=
<replaceable>address
</replaceable>[@
<replaceable>name
</replaceable>] [
<replaceable>weight
</replaceable>]
</varname></term>
1314 <para>Configures multipath route. Multipath routing is the technique of using multiple
1315 alternative paths through a network. Takes gateway address. Optionally, takes a network
1316 interface name or index separated with
<literal>@
</literal>, and a weight in
1.
.256 for
1317 this multipath route separated with whitespace. This setting can be specified multiple
1318 times. If an empty string is assigned, then the all previous assignments are cleared.
</para>
1325 <title>[DHCPv4] Section Options
</title>
1326 <para>The
<literal>[DHCPv4]
</literal> section configures the
1327 DHCPv4 client, if it is enabled with the
1328 <varname>DHCP=
</varname> setting described above:
</para>
1330 <variablelist class='network-directives'
>
1332 <term><varname>UseDNS=
</varname></term>
1334 <para>When true (the default), the DNS servers received
1335 from the DHCP server will be used and take precedence over
1336 any statically configured ones.
</para>
1338 <para>This corresponds to the
<option>nameserver
</option>
1339 option in
<citerefentry
1340 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1344 <term><varname>RoutesToDNS=
</varname></term>
1346 <para>When true, the routes to the DNS servers received from the DHCP server will be
1347 configured. When
<varname>UseDNS=
</varname> is disabled, this setting is ignored.
1348 Defaults to false.
</para>
1352 <term><varname>UseNTP=
</varname></term>
1354 <para>When true (the default), the NTP servers received
1355 from the DHCP server will be used by systemd-timesyncd
1356 and take precedence over any statically configured ones.
</para>
1360 <term><varname>UseSIP=
</varname></term>
1362 <para>When true (the default), the SIP servers received
1363 from the DHCP server will be saved at the state files and can be
1364 read via
<function>sd_network_link_get_sip_servers()
</function> function.
</para>
1368 <term><varname>UseMTU=
</varname></term>
1370 <para>When true, the interface maximum transmission unit
1371 from the DHCP server will be used on the current link.
1372 If
<varname>MTUBytes=
</varname> is set, then this setting is ignored.
1373 Defaults to false.
</para>
1377 <term><varname>Anonymize=
</varname></term>
1379 <para>Takes a boolean. When true, the options sent to the DHCP server will
1380 follow the
<ulink url=
"https://tools.ietf.org/html/rfc7844">RFC
7844</ulink>
1381 (Anonymity Profiles for DHCP Clients) to minimize disclosure of identifying information.
1382 Defaults to false.
</para>
1384 <para>This option should only be set to true when
1385 <varname>MACAddressPolicy=
</varname> is set to
<literal>random
</literal>
1387 project='man-pages'
><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
</para>
1389 <para>Note that this configuration will overwrite others.
1390 In concrete, the following variables will be ignored:
1391 <varname>SendHostname=
</varname>,
<varname>ClientIdentifier=
</varname>,
1392 <varname>UseRoutes=
</varname>,
<varname>UseMTU=
</varname>,
1393 <varname>VendorClassIdentifier=
</varname>,
<varname>UseTimezone=
</varname>.
</para>
1395 <para>With this option enabled DHCP requests will mimic those generated by Microsoft Windows, in
1396 order to reduce the ability to fingerprint and recognize installations. This means DHCP request
1397 sizes will grow and lease data will be more comprehensive than normally, though most of the
1398 requested data is not actually used.
</para>
1402 <term><varname>SendHostname=
</varname></term>
1404 <para>When true (the default), the machine's hostname will be sent to the DHCP server.
1405 Note that the machine's hostname must consist only of
7-bit ASCII lower-case characters and
1406 no spaces or dots, and be formatted as a valid DNS domain name. Otherwise, the hostname is not
1407 sent even if this is set to true.
</para>
1411 <term><varname>UseHostname=
</varname></term>
1413 <para>When true (the default), the hostname received from
1414 the DHCP server will be set as the transient hostname of the system.
1419 <term><varname>Hostname=
</varname></term>
1421 <para>Use this value for the hostname which is sent to the DHCP server, instead of machine's hostname.
1422 Note that the specified hostname must consist only of
7-bit ASCII lower-case characters and
1423 no spaces or dots, and be formatted as a valid DNS domain name.
</para>
1427 <term><varname>UseDomains=
</varname></term>
1429 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
1430 received from the DHCP server will be used as DNS search domain over this link, similar to the effect of
1431 the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name received from
1432 the DHCP server will be used for routing DNS queries only, but not for searching, similar to the effect of
1433 the
<option>Domains=
</option> setting when the argument is prefixed with
<literal>~
</literal>. Defaults to
1436 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
1437 of all host names, in particular of single-label names. It is generally safer to use the supplied domain
1438 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
1439 single-label names.
</para>
1441 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
1442 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1446 <term><varname>UseRoutes=
</varname></term>
1448 <para>When true (the default), the static routes will be requested from the DHCP server and added to the
1449 routing table with a metric of
1024, and a scope of
"global",
"link" or
"host", depending on the route's
1450 destination and gateway. If the destination is on the local host, e.g.,
127.x.x.x, or the same as the
1451 link's own address, the scope will be set to
"host". Otherwise if the gateway is null (a direct route), a
1452 "link" scope will be used. For anything else, scope defaults to
"global".
</para>
1457 <term><varname>UseTimezone=
</varname></term>
1459 <listitem><para>When true, the timezone received from the
1460 DHCP server will be set as timezone of the local
1461 system. Defaults to
<literal>no
</literal>.
</para></listitem>
1465 <term><varname>ClientIdentifier=
</varname></term>
1467 <para>The DHCPv4 client identifier to use. Takes one of
<literal>mac
</literal>,
<literal>duid
</literal> or
<literal>duid-only
</literal>.
1468 If set to
<literal>mac
</literal>, the MAC address of the link is used.
1469 If set to
<literal>duid
</literal>, an RFC4361-compliant Client ID, which is the combination of IAID and DUID (see below), is used.
1470 If set to
<literal>duid-only
</literal>, only DUID is used, this may not be RFC compliant, but some setups may require to use this.
1471 Defaults to
<literal>duid
</literal>.
</para>
1476 <term><varname>VendorClassIdentifier=
</varname></term>
1478 <para>The vendor class identifier used to identify vendor
1479 type and configuration.
</para>
1484 <term><varname>UserClass=
</varname></term>
1486 <para>A DHCPv4 client can use UserClass option to identify the type or category of user or applications
1487 it represents. The information contained in this option is a string that represents the user class of which
1488 the client is a member. Each class sets an identifying string of information to be used by the DHCP
1489 service to classify clients. Takes a whitespace-separated list of strings.
</para>
1494 <term><varname>MaxAttempts=
</varname></term>
1496 <para>Specifies how many times the DHCPv4 client configuration should be attempted. Takes a
1497 number or
<literal>infinity
</literal>. Defaults to
<literal>infinity
</literal>.
1498 Note that the time between retries is increased exponentially, so the network will not be
1499 overloaded even if this number is high.
</para>
1504 <term><varname>DUIDType=
</varname></term>
1506 <para>Override the global
<varname>DUIDType
</varname> setting for this network. See
1507 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1508 for a description of possible values.
</para>
1513 <term><varname>DUIDRawData=
</varname></term>
1515 <para>Override the global
<varname>DUIDRawData
</varname> setting for this network. See
1516 <citerefentry><refentrytitle>networkd.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1517 for a description of possible values.
</para>
1522 <term><varname>IAID=
</varname></term>
1524 <para>The DHCP Identity Association Identifier (IAID) for the interface, a
32-bit unsigned integer.
</para>
1529 <term><varname>RequestBroadcast=
</varname></term>
1531 <para>Request the server to use broadcast messages before
1532 the IP address has been configured. This is necessary for
1533 devices that cannot receive RAW packets, or that cannot
1534 receive packets at all before an IP address has been
1535 configured. On the other hand, this must not be enabled on
1536 networks where broadcasts are filtered out.
</para>
1541 <term><varname>RouteMetric=
</varname></term>
1543 <para>Set the routing metric for routes specified by the
1549 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
1551 <para>The table identifier for DHCP routes (a number between
1 and
4294967295, or
0 to unset).
1552 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1554 <para>When used in combination with
<varname>VRF=
</varname> the
1555 VRF's routing table is used unless this parameter is specified.
1561 <term><varname>RouteMTUBytes=
</varname></term>
1563 <para>Specifies the MTU for the DHCP routes. Please see the [Route] section for further details.
</para>
1568 <term><varname>ListenPort=
</varname></term>
1570 <para>Allow setting custom port for the DHCP client to listen on.
</para>
1575 <term><varname>SendRelease=
</varname></term>
1577 <para>When true, the DHCPv4 client sends a DHCP release packet when it stops.
1578 Defaults to true.
</para>
1583 <term><varname>SendDecline=
</varname></term>
1585 <para>A boolen. When
<literal>true
</literal>, DHCPv4 clients receives IP address from DHCP server.
1586 After new IP is received, DHCPv4 performs IPv4 Duplicate Address Detection. If duplicate use of IP is detected
1587 the DHCPv4 client rejects the IP by sending a DHCPDECLINE packet DHCP clients try to obtain an IP address again.
1588 See
<ulink url=
"https://tools.ietf.org/html/rfc5227">RFC
5224</ulink>.
1589 Defaults to
<literal>unset
</literal>.
</para>
1594 <term><varname>BlackList=
</varname></term>
1596 <para>A whitespace-separated list of IPv4 addresses. DHCP offers from servers in the list are rejected.
</para>
1601 <term><varname>RequestOptions=
</varname></term>
1603 <para>A whitespace-separated list of integers in the range
1–
254.
</para>
1608 <term><varname>SendOption=
</varname></term>
1610 <para>Send an arbitrary option in the DHCPv4 request. Takes a DHCP option number, data type
1611 and data separated with a colon
1612 (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1613 The option number must be an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
1614 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
1615 <literal>string
</literal>. Special characters in the data string may be escaped using
1616 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1617 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1618 then all options specified earlier are cleared. Defaults to unset.
</para>
1625 <title>[DHCPv6] Section Options
</title>
1626 <para>The
<literal>[DHCPv6]
</literal> section configures the DHCPv6 client, if it is enabled with the
1627 <varname>DHCP=
</varname> setting described above, or invoked by the IPv6 Router Advertisement:
</para>
1629 <variablelist class='network-directives'
>
1631 <term><varname>UseDNS=
</varname></term>
1632 <term><varname>UseNTP=
</varname></term>
1634 <para>As in the
<literal>[DHCPv4]
</literal> section.
</para>
1639 <term><varname>RapidCommit=
</varname></term>
1641 <para>Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6 server through
1642 a rapid two-message exchange (solicit and reply). When the rapid commit option is enabled by both
1643 the DHCPv6 client and the DHCPv6 server, the two-message exchange is used, rather than the default
1644 four-method exchange (solicit, advertise, request, and reply). The two-message exchange provides
1645 faster client configuration and is beneficial in environments in which networks are under a heavy load.
1646 See
<ulink url=
"https://tools.ietf.org/html/rfc3315#section-17.2.1">RFC
3315</ulink> for details.
1647 Defaults to true.
</para>
1652 <term><varname>ForceDHCPv6PDOtherInformation=
</varname></term>
1654 <para>Takes a boolean that enforces DHCPv6 stateful mode when the 'Other information' bit is set in
1655 Router Advertisement messages. By default setting only the 'O' bit in Router Advertisements
1656 makes DHCPv6 request network information in a stateless manner using a two-message Information
1657 Request and Information Reply message exchange.
1658 <ulink url=
"https://tools.ietf.org/html/rfc7084">RFC
7084</ulink>, requirement WPD-
4, updates
1659 this behavior for a Customer Edge router so that stateful DHCPv6 Prefix Delegation is also
1660 requested when only the 'O' bit is set in Router Advertisements. This option enables such a CE
1661 behavior as it is impossible to automatically distinguish the intention of the 'O' bit otherwise.
1662 By default this option is set to 'false', enable it if no prefixes are delegated when the device
1663 should be acting as a CE router.
</para>
1668 <term><varname>PrefixDelegationHint=
</varname></term>
1670 <para>Takes an IPv6 address with prefix length as
<varname>Address=
</varname> in
1671 the
"[Network]" section. Specifies the DHCPv6 client for the requesting router to include
1672 a prefix-hint in the DHCPv6 solicitation. Prefix ranges
1-
128. Defaults to unset.
</para>
1679 <title>[IPv6AcceptRA] Section Options
</title>
1680 <para>The
<literal>[IPv6AcceptRA]
</literal> section configures the IPv6 Router Advertisement
1681 (RA) client, if it is enabled with the
<varname>IPv6AcceptRA=
</varname> setting described
1684 <variablelist class='network-directives'
>
1686 <term><varname>UseDNS=
</varname></term>
1688 <para>When true (the default), the DNS servers received in the Router Advertisement will be used and take
1689 precedence over any statically configured ones.
</para>
1691 <para>This corresponds to the
<option>nameserver
</option> option in
<citerefentry
1692 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1697 <term><varname>UseDomains=
</varname></term>
1699 <para>Takes a boolean, or the special value
<literal>route
</literal>. When true, the domain name
1700 received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link, similar to
1701 the effect of the
<option>Domains=
</option> setting. If set to
<literal>route
</literal>, the domain name
1702 received via IPv6 RA will be used for routing DNS queries only, but not for searching, similar to the
1703 effect of the
<option>Domains=
</option> setting when the argument is prefixed with
1704 <literal>~
</literal>. Defaults to false.
</para>
1706 <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
1707 of all host names, in particular of single-label names. It is generally safer to use the supplied domain
1708 only as routing domain, rather than as search domain, in order to not have it affect local resolution of
1709 single-label names.
</para>
1711 <para>When set to true, this setting corresponds to the
<option>domain
</option> option in
<citerefentry
1712 project='man-pages'
><refentrytitle>resolv.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
1717 <term><varname>RouteTable=
<replaceable>num
</replaceable></varname></term>
1719 <para>The table identifier for the routes received in the Router Advertisement
1720 (a number between
1 and
4294967295, or
0 to unset).
1721 The table can be retrieved using
<command>ip route show table
<replaceable>num
</replaceable></command>.
1727 <term><varname>UseAutonomousPrefix=
</varname></term>
1729 <para>When true (the default), the autonomous prefix received in the Router Advertisement will be used and take
1730 precedence over any statically configured ones.
</para>
1735 <term><varname>UseOnLinkPrefix=
</varname></term>
1737 <para>When true (the default), the onlink prefix received in the Router Advertisement will be used and take
1738 precedence over any statically configured ones.
</para>
1743 <term><varname>BlackList=
</varname></term>
1745 <para>A whitespace-separated list of IPv6 prefixes. IPv6 prefixes supplied via router advertisements in the list are ignored.
</para>
1753 <title>[DHCPServer] Section Options
</title>
1754 <para>The
<literal>[DHCPServer]
</literal> section contains
1755 settings for the DHCP server, if enabled via the
1756 <varname>DHCPServer=
</varname> option described above:
</para>
1758 <variablelist class='network-directives'
>
1761 <term><varname>PoolOffset=
</varname></term>
1762 <term><varname>PoolSize=
</varname></term>
1764 <listitem><para>Configures the pool of addresses to hand out. The pool
1765 is a contiguous sequence of IP addresses in the subnet configured for
1766 the server address, which does not include the subnet nor the broadcast
1767 address.
<varname>PoolOffset=
</varname> takes the offset of the pool
1768 from the start of subnet, or zero to use the default value.
1769 <varname>PoolSize=
</varname> takes the number of IP addresses in the
1770 pool or zero to use the default value. By default, the pool starts at
1771 the first address after the subnet address and takes up the rest of
1772 the subnet, excluding the broadcast address. If the pool includes
1773 the server address (the default), this is reserved and not handed
1774 out to clients.
</para></listitem>
1778 <term><varname>DefaultLeaseTimeSec=
</varname></term>
1779 <term><varname>MaxLeaseTimeSec=
</varname></term>
1781 <listitem><para>Control the default and maximum DHCP lease
1782 time to pass to clients. These settings take time values in seconds or
1783 another common time unit, depending on the suffix. The default
1784 lease time is used for clients that did not ask for a specific
1785 lease time. If a client asks for a lease time longer than the
1786 maximum lease time, it is automatically shortened to the
1787 specified time. The default lease time defaults to
1h, the
1788 maximum lease time to
12h. Shorter lease times are beneficial
1789 if the configuration data in DHCP leases changes frequently
1790 and clients shall learn the new settings with shorter
1791 latencies. Longer lease times reduce the generated DHCP
1792 network traffic.
</para></listitem>
1796 <term><varname>EmitDNS=
</varname></term>
1797 <term><varname>DNS=
</varname></term>
1799 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
1800 to clients shall contain DNS server information. Defaults to
<literal>yes
</literal>.
1801 The DNS servers to pass to clients may be configured with the
1802 <varname>DNS=
</varname> option, which takes a list of IPv4
1803 addresses. If the
<varname>EmitDNS=
</varname> option is
1804 enabled but no servers configured, the servers are
1805 automatically propagated from an
"uplink" interface that has
1806 appropriate servers set. The
"uplink" interface is determined
1807 by the default route of the system with the highest
1808 priority. Note that this information is acquired at the time
1809 the lease is handed out, and does not take uplink interfaces
1810 into account that acquire DNS or NTP server information at a
1811 later point. DNS server propagation does not take
1812 <filename>/etc/resolv.conf
</filename> into account. Also, note
1813 that the leases are not refreshed if the uplink network
1814 configuration changes. To ensure clients regularly acquire the
1815 most current uplink DNS server information, it is thus
1816 advisable to shorten the DHCP lease time via
1817 <varname>MaxLeaseTimeSec=
</varname> described
1818 above.
</para></listitem>
1822 <term><varname>EmitNTP=
</varname></term>
1823 <term><varname>NTP=
</varname></term>
1825 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
1826 <varname>DNS=
</varname> settings described above, these
1827 settings configure whether and what NTP server information
1828 shall be emitted as part of the DHCP lease. The same syntax,
1829 propagation semantics and defaults apply as for
1830 <varname>EmitDNS=
</varname> and
1831 <varname>DNS=
</varname>.
</para></listitem>
1835 <term><varname>EmitSIP=
</varname></term>
1836 <term><varname>SIP=
</varname></term>
1838 <listitem><para>Similar to the
<varname>EmitDNS=
</varname> and
1839 <varname>DNS=
</varname> settings described above, these
1840 settings configure whether and what SIP server information
1841 shall be emitted as part of the DHCP lease. The same syntax,
1842 propagation semantics and defaults apply as for
1843 <varname>EmitDNS=
</varname> and
1844 <varname>DNS=
</varname>.
</para></listitem>
1848 <term><varname>EmitRouter=
</varname></term>
1850 <listitem><para>Similar to the
<varname>EmitDNS=
</varname>
1851 setting described above, this setting configures whether the
1852 DHCP lease should contain the router option. The same syntax,
1853 propagation semantics and defaults apply as for
1854 <varname>EmitDNS=
</varname>.
</para></listitem>
1858 <term><varname>EmitTimezone=
</varname></term>
1859 <term><varname>Timezone=
</varname></term>
1861 <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
1862 to clients shall contain timezone information. Defaults to
<literal>yes
</literal>. The
1863 <varname>Timezone=
</varname> setting takes a timezone string
1864 (such as
<literal>Europe/Berlin
</literal> or
1865 <literal>UTC
</literal>) to pass to clients. If no explicit
1866 timezone is set, the system timezone of the local host is
1867 propagated, as determined by the
1868 <filename>/etc/localtime
</filename> symlink.
</para></listitem>
1872 <term><varname>SendOption=
</varname></term>
1874 <para>Send a raw option with value via DHCPv4 server. Takes a DHCP option number, data type
1875 and data (
<literal><replaceable>option
</replaceable>:
<replaceable>type
</replaceable>:
<replaceable>value
</replaceable></literal>).
1876 The option number is an integer in the range
1.
.254. The type takes one of
<literal>uint8
</literal>,
1877 <literal>uint16
</literal>,
<literal>uint32
</literal>,
<literal>ipv4address
</literal>, or
1878 <literal>string
</literal>. Special characters in the data string may be escaped using
1879 <ulink url=
"https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
1880 escapes
</ulink>. This setting can be specified multiple times. If an empty string is specified,
1881 then all options specified earlier are cleared. Defaults to unset.
</para>
1889 <title>[IPv6PrefixDelegation] Section Options
</title>
1890 <para>The
<literal>[IPv6PrefixDelegation]
</literal> section contains
1891 settings for sending IPv6 Router Advertisements and whether to act as
1892 a router, if enabled via the
<varname>IPv6PrefixDelegation=
</varname>
1893 option described above. IPv6 network prefixes are defined with one or
1894 more
<literal>[IPv6Prefix]
</literal> sections.
</para>
1896 <variablelist class='network-directives'
>
1899 <term><varname>Managed=
</varname></term>
1900 <term><varname>OtherInformation=
</varname></term>
1902 <listitem><para>Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6
1903 addresses on the network link when
<varname>Managed=
</varname>
1904 is set to
<literal>true
</literal> or if only additional network
1905 information can be obtained via DHCPv6 for the network link when
1906 <varname>OtherInformation=
</varname> is set to
1907 <literal>true
</literal>. Both settings default to
1908 <literal>false
</literal>, which means that a DHCPv6 server is not being
1909 used.
</para></listitem>
1913 <term><varname>RouterLifetimeSec=
</varname></term>
1915 <listitem><para>Takes a timespan. Configures the IPv6 router lifetime in seconds. If set,
1916 this host also announces itself in Router Advertisements as an IPv6
1917 router for the network link. When unset, the host is not acting as a router.
</para>
1922 <term><varname>RouterPreference=
</varname></term>
1924 <listitem><para>Configures IPv6 router preference if
1925 <varname>RouterLifetimeSec=
</varname> is non-zero. Valid values are
1926 <literal>high
</literal>,
<literal>medium
</literal> and
1927 <literal>low
</literal>, with
<literal>normal
</literal> and
1928 <literal>default
</literal> added as synonyms for
1929 <literal>medium
</literal> just to make configuration easier. See
1930 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
1931 for details. Defaults to
<literal>medium
</literal>.
</para></listitem>
1935 <term><varname>EmitDNS=
</varname></term>
1936 <term><varname>DNS=
</varname></term>
1938 <listitem><para><varname>DNS=
</varname> specifies a list of recursive DNS server IPv6 addresses
1939 that are distributed via Router Advertisement messages when
<varname>EmitDNS=
</varname> is
1940 true.
<varname>DNS=
</varname> also takes special value
<literal>_link_local
</literal>; in that
1941 case the IPv6 link local address is distributed. If
<varname>DNS=
</varname> is empty, DNS
1942 servers are read from the
<literal>[Network]
</literal> section. If the
1943 <literal>[Network]
</literal> section does not contain any DNS servers either, DNS servers from
1944 the uplink with the highest priority default route are used. When
<varname>EmitDNS=
</varname>
1945 is false, no DNS server information is sent in Router Advertisement messages.
1946 <varname>EmitDNS=
</varname> defaults to true.
1951 <term><varname>EmitDomains=
</varname></term>
1952 <term><varname>Domains=
</varname></term>
1954 <listitem><para>A list of DNS search domains distributed via Router
1955 Advertisement messages when
<varname>EmitDomains=
</varname> is true. If
1956 <varname>Domains=
</varname> is empty, DNS search domains are read from the
1957 <literal>[Network]
</literal> section. If the
<literal>[Network]
</literal>
1958 section does not contain any DNS search domains either, DNS search
1959 domains from the uplink with the highest priority default route are
1960 used. When
<varname>EmitDomains=
</varname> is false, no DNS search domain
1961 information is sent in Router Advertisement messages.
1962 <varname>EmitDomains=
</varname> defaults to true.
1967 <term><varname>DNSLifetimeSec=
</varname></term>
1969 <listitem><para>Lifetime in seconds for the DNS server addresses listed
1970 in
<varname>DNS=
</varname> and search domains listed in
1971 <varname>Domains=
</varname>.
</para></listitem>
1978 <title>[IPv6Prefix] Section Options
</title>
1979 <para>One or more
<literal>[IPv6Prefix]
</literal> sections contain the IPv6
1980 prefixes that are announced via Router Advertisements. See
1981 <ulink url=
"https://tools.ietf.org/html/rfc4861">RFC
4861</ulink>
1982 for further details.
</para>
1984 <variablelist class='network-directives'
>
1987 <term><varname>AddressAutoconfiguration=
</varname></term>
1988 <term><varname>OnLink=
</varname></term>
1990 <listitem><para>Takes a boolean to specify whether IPv6 addresses can be
1991 autoconfigured with this prefix and whether the prefix can be used for
1992 onlink determination. Both settings default to
<literal>true
</literal>
1993 in order to ease configuration.
1998 <term><varname>Prefix=
</varname></term>
2000 <listitem><para>The IPv6 prefix that is to be distributed to hosts.
2001 Similarly to configuring static IPv6 addresses, the setting is
2002 configured as an IPv6 prefix and its prefix length, separated by a
2003 <literal>/
</literal> character. Use multiple
2004 <literal>[IPv6Prefix]
</literal> sections to configure multiple IPv6
2005 prefixes since prefix lifetimes, address autoconfiguration and onlink
2006 status may differ from one prefix to another.
</para></listitem>
2010 <term><varname>PreferredLifetimeSec=
</varname></term>
2011 <term><varname>ValidLifetimeSec=
</varname></term>
2013 <listitem><para>Preferred and valid lifetimes for the prefix measured in
2014 seconds.
<varname>PreferredLifetimeSec=
</varname> defaults to
604800
2015 seconds (one week) and
<varname>ValidLifetimeSec=
</varname> defaults
2016 to
2592000 seconds (
30 days).
</para></listitem>
2023 <title>[IPv6RoutePrefix] Section Options
</title>
2024 <para>One or more
<literal>[IPv6RoutePrefix]
</literal> sections contain the IPv6
2025 prefix routes that are announced via Router Advertisements. See
2026 <ulink url=
"https://tools.ietf.org/html/rfc4191">RFC
4191</ulink>
2027 for further details.
</para>
2029 <variablelist class='network-directives'
>
2032 <term><varname>Route=
</varname></term>
2034 <listitem><para>The IPv6 route that is to be distributed to hosts.
2035 Similarly to configuring static IPv6 routes, the setting is
2036 configured as an IPv6 prefix routes and its prefix route length,
2037 separated by a
<literal>/
</literal> character. Use multiple
2038 <literal>[IPv6PrefixRoutes]
</literal> sections to configure multiple IPv6
2039 prefix routes.
</para></listitem>
2043 <term><varname>LifetimeSec=
</varname></term>
2045 <listitem><para>Lifetime for the route prefix measured in
2046 seconds.
<varname>LifetimeSec=
</varname> defaults to
604800 seconds (one week).
2054 <title>[Bridge] Section Options
</title>
2055 <para>The
<literal>[Bridge]
</literal> section accepts the
2056 following keys.
</para>
2057 <variablelist class='network-directives'
>
2059 <term><varname>UnicastFlood=
</varname></term>
2061 <para>Takes a boolean. Controls whether the bridge should flood
2062 traffic for which an FDB entry is missing and the destination
2063 is unknown through this port. When unset, the kernel's default will be used.
2068 <term><varname>MulticastFlood=
</varname></term>
2070 <para>Takes a boolean. Controls whether the bridge should flood
2071 traffic for which an MDB entry is missing and the destination
2072 is unknown through this port. When unset, the kernel's default will be used.
2077 <term><varname>MulticastToUnicast=
</varname></term>
2079 <para>Takes a boolean. Multicast to unicast works on top of the multicast snooping feature of
2080 the bridge. Which means unicast copies are only delivered to hosts which are interested in it.
2081 When unset, the kernel's default will be used.
2086 <term><varname>NeighborSuppression=
</varname></term>
2088 <para>Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for
2089 this port. When unset, the kernel's default will be used.
2094 <term><varname>Learning=
</varname></term>
2096 <para>Takes a boolean. Configures whether MAC address learning is enabled for
2097 this port. When unset, the kernel's default will be used.
2102 <term><varname>HairPin=
</varname></term>
2104 <para>Takes a boolean. Configures whether traffic may be sent back
2105 out of the port on which it was received. When this flag is false, and the bridge
2106 will not forward traffic back out of the receiving port.
2107 When unset, the kernel's default will be used.
</para>
2111 <term><varname>UseBPDU=
</varname></term>
2113 <para>Takes a boolean. Configures whether STP Bridge Protocol Data Units will be
2114 processed by the bridge port. When unset, the kernel's default will be used.
</para>
2118 <term><varname>FastLeave=
</varname></term>
2120 <para>Takes a boolean. This flag allows the bridge to immediately stop multicast
2121 traffic on a port that receives an IGMP Leave message. It is only used with
2122 IGMP snooping if enabled on the bridge. When unset, the kernel's default will be used.
</para>
2126 <term><varname>AllowPortToBeRoot=
</varname></term>
2128 <para>Takes a boolean. Configures whether a given port is allowed to
2129 become a root port. Only used when STP is enabled on the bridge.
2130 When unset, the kernel's default will be used.
</para>
2134 <term><varname>ProxyARP=
</varname></term>
2136 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port.
2137 When unset, the kernel's default will be used.
</para>
2141 <term><varname>ProxyARPWiFi=
</varname></term>
2143 <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port
2144 which meets extended requirements by IEEE
802.11 and Hotspot
2.0 specifications.
2145 When unset, the kernel's default will be used.
</para>
2149 <term><varname>MulticastRouter=
</varname></term>
2151 <para>Configures this port for having multicast routers attached. A port with a multicast
2152 router will receive all multicast traffic. Takes one of
<literal>no
</literal>
2153 to disable multicast routers on this port,
<literal>query
</literal> to let the system detect
2154 the presence of routers,
<literal>permanent
</literal> to permanently enable multicast traffic
2155 forwarding on this port, or
<literal>temporary
</literal> to enable multicast routers temporarily
2156 on this port, not depending on incoming queries. When unset, the kernel's default will be used.
</para>
2160 <term><varname>Cost=
</varname></term>
2162 <para>Sets the
"cost" of sending packets of this interface.
2163 Each port in a bridge may have a different speed and the cost
2164 is used to decide which link to use. Faster interfaces
2165 should have lower costs. It is an integer value between
1 and
2170 <term><varname>Priority=
</varname></term>
2172 <para>Sets the
"priority" of sending packets on this interface.
2173 Each port in a bridge may have a different priority which is used
2174 to decide which link to use. Lower value means higher priority.
2175 It is an integer value between
0 to
63. Networkd does not set any
2176 default, meaning the kernel default value of
32 is used.
</para>
2182 <title>[BridgeFDB] Section Options
</title>
2183 <para>The
<literal>[BridgeFDB]
</literal> section manages the
2184 forwarding database table of a port and accepts the following
2185 keys. Specify several
<literal>[BridgeFDB]
</literal> sections to
2186 configure several static MAC table entries.
</para>
2188 <variablelist class='network-directives'
>
2190 <term><varname>MACAddress=
</varname></term>
2192 <para>As in the
<literal>[Network]
</literal> section. This
2193 key is mandatory.
</para>
2197 <term><varname>Destination=
</varname></term>
2199 <para>Takes an IP address of the destination VXLAN tunnel endpoint.
</para>
2203 <term><varname>VLANId=
</varname></term>
2205 <para>The VLAN ID for the new static MAC table entry. If
2206 omitted, no VLAN ID information is appended to the new static MAC
2211 <term><varname>VNI=
</varname></term>
2213 <para>The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to
2214 the remote VXLAN tunnel endpoint. Takes a number in the range
1-
16777215.
2215 Defaults to unset.
</para>
2219 <term><varname>AssociatedWith=
</varname></term>
2221 <para>Specifies where the address is associated with. Takes one of
<literal>use
</literal>,
2222 <literal>self
</literal>,
<literal>master
</literal> or
<literal>router
</literal>.
2223 <literal>use
</literal> means the address is in use. User space can use this option to
2224 indicate to the kernel that the fdb entry is in use.
<literal>self
</literal> means
2225 the address is associated with the port drivers fdb. Usually hardware.
<literal>master
</literal>
2226 means the address is associated with master devices fdb.
<literal>router
</literal> means
2227 the destination address is associated with a router. Note that it's valid if the referenced
2228 device is a VXLAN type device and has route shortcircuit enabled. Defaults to
<literal>self
</literal>.
</para>
2235 <title>[CAN] Section Options
</title>
2236 <para>The
<literal>[CAN]
</literal> section manages the Controller Area Network (CAN bus) and accepts the
2237 following keys.
</para>
2238 <variablelist class='network-directives'
>
2240 <term><varname>BitRate=
</varname></term>
2242 <para>The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the base of
1000 can
2243 be used here.
</para>
2247 <term><varname>SamplePoint=
</varname></term>
2249 <para>Optional sample point in percent with one decimal (e.g.
<literal>75%
</literal>,
2250 <literal>87.5%
</literal>) or permille (e.g.
<literal>875‰
</literal>).
</para>
2254 <term><varname>RestartSec=
</varname></term>
2256 <para>Automatic restart delay time. If set to a non-zero value, a restart of the CAN controller will be
2257 triggered automatically in case of a bus-off condition after the specified delay time. Subsecond delays can
2258 be specified using decimals (e.g.
<literal>0.1s
</literal>) or a
<literal>ms
</literal> or
2259 <literal>us
</literal> postfix. Using
<literal>infinity
</literal> or
<literal>0</literal> will turn the
2260 automatic restart off. By default automatic restart is disabled.
</para>
2264 <term><varname>TripleSampling=
</varname></term>
2266 <para>Takes a boolean. When
<literal>yes
</literal>, three samples (instead of one) are used to determine
2267 the value of a received bit by majority rule. When unset, the kernel's default will be used.
</para>
2274 <title>[QDisc] Section Options
</title>
2275 <para>The
<literal>[QDisc]
</literal> section manages the traffic control queueing discipline (qdisc).
</para>
2277 <variablelist class='network-directives'
>
2279 <term><varname>Parent=
</varname></term>
2281 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>clsact
</literal>
2282 or
<literal>ingress
</literal>. This is mandatory.
</para>
2287 <term><varname>Handle=
</varname></term>
2289 <para>Specifies the major number of unique identifier of the qdisc, known as the handle.
2290 Takes a number in hexadecimal ranges
1 to ffff. Defaults to unset.
</para>
2297 <title>[NetworkEmulator] Section Options
</title>
2298 <para>The
<literal>[NetworkEmulator]
</literal> section manages the queueing discipline (qdisc) of
2299 the network emulator. It can be used to configure the kernel packet scheduler and simulate packet
2300 delay and loss for UDP or TCP applications, or limit the bandwidth usage of a particular service to
2301 simulate internet connections.
</para>
2303 <variablelist class='network-directives'
>
2305 <term><varname>Parent=
</varname></term>
2307 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>root
</literal>,
2308 <literal>clsact
</literal> or
<literal>ingress
</literal>. Defaults to
<literal>root
</literal>.
</para>
2313 <term><varname>Handle=
</varname></term>
2315 <para>Specifies the major number of unique identifier of the qdisc, known as the handle.
2316 Takes a number in hexadecimal ranges
1 to ffff. Defaults to unset.
</para>
2321 <term><varname>DelaySec=
</varname></term>
2323 <para>Specifies the fixed amount of delay to be added to all packets going out of the
2324 interface. Defaults to unset.
</para>
2329 <term><varname>DelayJitterSec=
</varname></term>
2331 <para>Specifies the chosen delay to be added to the packets outgoing to the network
2332 interface. Defaults to unset.
</para>
2337 <term><varname>PacketLimit=
</varname></term>
2339 <para>Specifies the maximum number of packets the qdisc may hold queued at a time.
2340 An unsigned integer ranges
0 to
4294967294. Defaults to
1000.
</para>
2345 <term><varname>LossRate=
</varname></term>
2347 <para>Specifies an independent loss probability to be added to the packets outgoing from the
2348 network interface. Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
2353 <term><varname>DuplicateRate=
</varname></term>
2355 <para>Specifies that the chosen percent of packets is duplicated before queuing them.
2356 Takes a percentage value, suffixed with
"%". Defaults to unset.
</para>
2363 <title>[TokenBucketFilter] Section Options
</title>
2364 <para>The
<literal>[TokenBucketFilter]
</literal> section manages the queueing discipline (qdisc) of
2365 token bucket filter (tbf).
</para>
2367 <variablelist class='network-directives'
>
2369 <term><varname>Parent=
</varname></term>
2371 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>root
</literal>,
2372 <literal>clsact
</literal> or
<literal>ingress
</literal>. Defaults to
<literal>root
</literal>.
</para>
2377 <term><varname>Handle=
</varname></term>
2379 <para>Specifies the major number of unique identifier of the qdisc, known as the handle.
2380 Takes a number in hexadecimal ranges
1 to ffff. Defaults to unset.
</para>
2385 <term><varname>LatencySec=
</varname></term>
2387 <para>Specifies the latency parameter, which specifies the maximum amount of time a
2388 packet can sit in the Token Bucket Filter (TBF). Defaults to unset.
</para>
2393 <term><varname>LimitSize=
</varname></term>
2395 <para>Takes the number of bytes that can be queued waiting for tokens to become available.
2396 When the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or Gigabytes,
2397 respectively, to the base of
1000. Defaults to unset.
</para>
2402 <term><varname>Burst=
</varname></term>
2404 <para>Specifies the size of the bucket. This is the maximum amount of bytes that tokens
2405 can be available for instantaneous transfer. When the size is suffixed with K, M, or G, it is
2406 parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1000. Defaults to
2412 <term><varname>Rate=
</varname></term>
2414 <para>Specifies the device specific bandwidth. When suffixed with K, M, or G, the specified
2415 bandwidth is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
1000.
2416 Defaults to unset.
</para>
2421 <term><varname>MPUBytes=
</varname></term>
2423 <para>The Minimum Packet Unit (MPU) determines the minimal token usage (specified in bytes)
2424 for a packet. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
2425 Megabytes, or Gigabytes, respectively, to the base of
1000. Defaults to zero.
</para>
2430 <term><varname>PeakRate=
</varname></term>
2432 <para>Takes the maximum depletion rate of the bucket. When suffixed with K, M, or G, the
2433 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
2434 1000. Defaults to unset.
</para>
2439 <term><varname>MTUBytes=
</varname></term>
2441 <para>Specifies the size of the peakrate bucket. When suffixed with K, M, or G, the specified
2442 size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1000.
2443 Defaults to unset.
</para>
2450 <title>[StochasticFairnessQueueing] Section Options
</title>
2451 <para>The
<literal>[StochasticFairnessQueueing]
</literal> section manages the queueing discipline
2452 (qdisc) of stochastic fairness queueing (sfq).
</para>
2454 <variablelist class='network-directives'
>
2456 <term><varname>Parent=
</varname></term>
2458 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>root
</literal>,
2459 <literal>clsact
</literal> or
<literal>ingress
</literal>. Defaults to
<literal>root
</literal>.
</para>
2464 <term><varname>Handle=
</varname></term>
2466 <para>Specifies the major number of unique identifier of the qdisc, known as the handle.
2467 Takes a number in hexadecimal ranges
1 to ffff. Defaults to unset.
</para>
2472 <term><varname>PerturbPeriodSec=
</varname></term>
2474 <para>Specifies the interval in seconds for queue algorithm perturbation. Defaults to unset.
</para>
2481 <title>[ControlledDelay] Section Options
</title>
2482 <para>The
<literal>[ControlledDelay]
</literal> section manages the queueing discipline (qdisc) of
2483 controlled delay (CoDel).
</para>
2485 <variablelist class='network-directives'
>
2487 <term><varname>Parent=
</varname></term>
2489 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>root
</literal>,
2490 <literal>clsact
</literal> or
<literal>ingress
</literal>. Defaults to
<literal>root
</literal>.
</para>
2495 <term><varname>Handle=
</varname></term>
2497 <para>Specifies the major number of unique identifier of the qdisc, known as the handle.
2498 Takes a number in hexadecimal ranges
1 to ffff. Defaults to unset.
</para>
2503 <term><varname>PacketLimit=
</varname></term>
2505 <para>Specifies the hard lmit on the queue size in number of packets. When this limit is reached, incoming packets are
2506 dropped. An unsigned integer ranges
0 to
4294967294. Defaults to unset and kernel's default is used.
</para>
2511 <term><varname>TargetSec=
</varname></term>
2513 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
2514 Defaults to unset and kernel's default is used.
</para>
2519 <term><varname>IntervalSec=
</varname></term>
2521 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
2522 become too stale. Defaults to unset and kernel's default is used.
</para>
2527 <term><varname>ECN=
</varname></term>
2529 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
2530 unset and kernel's default is used.
</para>
2535 <term><varname>CEThresholdSec=
</varname></term>
2537 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
2538 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
2545 <title>[FairQueueingControlledDelay] Section Options
</title>
2546 <para>The
<literal>[FairQueueingControlledDelay]
</literal> section manages the queueing discipline
2547 (qdisc) of fair queuing controlled delay (FQ-CoDel).
</para>
2549 <variablelist class='network-directives'
>
2551 <term><varname>Parent=
</varname></term>
2553 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>root
</literal>,
2554 <literal>clsact
</literal> or
<literal>ingress
</literal>. Defaults to
<literal>root
</literal>.
</para>
2559 <term><varname>Handle=
</varname></term>
2561 <para>Specifies the major number of unique identifier of the qdisc, known as the handle.
2562 Takes a number in hexadecimal ranges
1 to ffff. Defaults to unset.
</para>
2567 <term><varname>PacketLimit=
</varname></term>
2569 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
2570 dropped. Defaults to unset and kernel's default is used.
</para>
2575 <term><varname>MemoryLimit=
</varname></term>
2577 <para>Specifies the limit on the total number of bytes that can be queued in this FQ-CoDel instance.
2578 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
2579 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
2584 <term><varname>Flows=
</varname></term>
2586 <para>Specifies the number of flows into which the incoming packets are classified.
2587 Defaults to unset and kernel's default is used.
</para>
2592 <term><varname>TargetSec=
</varname></term>
2594 <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
2595 Defaults to unset and kernel's default is used.
</para>
2600 <term><varname>IntervalSec=
</varname></term>
2602 <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
2603 become too stale. Defaults to unset and kernel's default is used.
</para>
2608 <term><varname>Quantum=
</varname></term>
2610 <para>Specifies the number of bytes used as 'deficit' in the fair queuing algorithmtimespan.
2611 When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
2612 respectively, to the base of
1024. Defaults to unset and kernel's default is used.
</para>
2617 <term><varname>ECN=
</varname></term>
2619 <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
2620 unset and kernel's default is used.
</para>
2625 <term><varname>CEThresholdSec=
</varname></term>
2627 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
2628 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
2635 <title>[FairQueueing] Section Options
</title>
2636 <para>The
<literal>[FairQueueing]
</literal> section manages the queueing discipline
2637 (qdisc) of fair queue traffic policing (FQ).
</para>
2639 <variablelist class='network-directives'
>
2641 <term><varname>Parent=
</varname></term>
2643 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>root
</literal>,
2644 <literal>clsact
</literal> or
<literal>ingress
</literal>. Defaults to
<literal>root
</literal>.
</para>
2649 <term><varname>Handle=
</varname></term>
2651 <para>Specifies the major number of unique identifier of the qdisc, known as the handle.
2652 Takes a number in hexadecimal ranges
1 to ffff. Defaults to unset.
</para>
2657 <term><varname>PacketLimit=
</varname></term>
2659 <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
2660 dropped. Defaults to unset and kernel's default is used.
</para>
2665 <term><varname>FlowLimit=
</varname></term>
2667 <para>Specifies the hard limit on the maximum number of packets queued per flow. Defaults to
2668 unset and kernel's default is used.
</para>
2673 <term><varname>Quantum=
</varname></term>
2675 <para>Specifies the credit per dequeue RR round, i.e. the amount of bytes a flow is allowed
2676 to dequeue at once. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
2677 Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and kernel's
2678 default is used.
</para>
2683 <term><varname>InitialQuantum=
</varname></term>
2685 <para>Specifies the initial sending rate credit, i.e. the amount of bytes a new flow is
2686 allowed to dequeue initially. When suffixed with K, M, or G, the specified size is parsed as
2687 Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
1024. Defaults to unset and
2688 kernel's default is used.
</para>
2693 <term><varname>MaximumRate=
</varname></term>
2695 <para>Specifies the maximum sending rate of a flow. When suffixed with K, M, or G, the
2696 specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
2697 1000. Defaults to unset and kernel's default is used.
</para>
2702 <term><varname>Buckets=
</varname></term>
2704 <para>Specifies the size of the hash table used for flow lookups. Defaults to unset and
2705 kernel's default is used.
</para>
2710 <term><varname>OrphanMask=
</varname></term>
2712 <para>Takes an unsigned integer. For packets not owned by a socket, fq is able to mask a part
2713 of hash and reduce number of buckets associated with the traffic. Defaults to unset and
2714 kernel's default is used.
</para>
2719 <term><varname>Pacing=
</varname></term>
2721 <para>Takes a boolean, and enables or disables flow pacing. Defaults to unset and kernel's
2722 default is used.
</para>
2727 <term><varname>CEThresholdSec=
</varname></term>
2729 <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
2730 Congestion Experienced (CE). Defaults to unset and kernel's default is used.
</para>
2737 <title>[TrivialLinkEqualizer] Section Options
</title>
2738 <para>The
<literal>[TrivialLinkEqualizer]
</literal> section manages the queueing discipline (qdisc) of
2739 trivial link equalizer (teql).
</para>
2741 <variablelist class='network-directives'
>
2743 <term><varname>Parent=
</varname></term>
2745 <para>Specifies the parent Queueing Discipline (qdisc). Takes one of
<literal>root
</literal>,
2746 <literal>clsact
</literal> or
<literal>ingress
</literal>. Defaults to
<literal>root
</literal>.
</para>
2751 <term><varname>Handle=
</varname></term>
2753 <para>Specifies the major number of unique identifier of the qdisc, known as the handle.
2754 Takes a number in hexadecimal ranges
1 to ffff. Defaults to unset.
</para>
2759 <term><varname>Id=
</varname></term>
2761 <para>Specifies the interface ID
<literal>N
</literal> of teql. Defaults to
<literal>0</literal>.
2762 Note that when teql is used, currently, the module
<constant>sch_teql
</constant> with
2763 <constant>max_equalizers=N+
1</constant> option must be loaded before
2764 <command>systemd-networkd
</command> is started.
</para>
2771 <title>[BridgeVLAN] Section Options
</title>
2772 <para>The
<literal>[BridgeVLAN]
</literal> section manages the VLAN ID configuration of a bridge port and accepts
2773 the following keys. Specify several
<literal>[BridgeVLAN]
</literal> sections to configure several VLAN entries.
2774 The
<varname>VLANFiltering=
</varname> option has to be enabled, see
<literal>[Bridge]
</literal> section in
2775 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
2777 <variablelist class='network-directives'
>
2779 <term><varname>VLAN=
</varname></term>
2781 <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. VLAN IDs are valid
2782 from
1 to
4094.
</para>
2786 <term><varname>EgressUntagged=
</varname></term>
2788 <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
2789 <varname>EgressUntagged=
</varname> implicates the use of
<varname>VLAN=
</varname> above and will enable the
2790 VLAN ID for ingress as well. This can be either a single ID or a range M-N.
</para>
2794 <term><varname>PVID=
</varname></term>
2796 <para>The Port VLAN ID specified here is assigned to all untagged frames at ingress.
2797 <varname>PVID=
</varname> can be used only once. Configuring
<varname>PVID=
</varname> implicates the use of
2798 <varname>VLAN=
</varname> above and will enable the VLAN ID for ingress as well.
</para>
2805 <title>Examples
</title>
2807 <title>Static network configuration
</title>
2809 <programlisting># /etc/systemd/network/
50-static.network
2814 Address=
192.168.0.15/
24
2815 Gateway=
192.168.0.1</programlisting>
2817 <para>This brings interface
<literal>enp2s0
</literal> up with a static address. The
2818 specified gateway will be used for a default route.
</para>
2822 <title>DHCP on ethernet links
</title>
2824 <programlisting># /etc/systemd/network/
80-dhcp.network
2829 DHCP=yes
</programlisting>
2831 <para>This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with
2832 <literal>en
</literal> (i.e. ethernet interfaces).
</para>
2836 <title>IPv6 Prefix Delegation
</title>
2838 <programlisting># /etc/systemd/network/
55-ipv6-pd-upstream.network
2843 DHCP=ipv6
</programlisting>
2845 <programlisting># /etc/systemd/network/
56-ipv6-pd-downstream.network
2850 IPv6PrefixDelegation=dhcpv6
</programlisting>
2852 <para>This will enable IPv6 PD on the interface enp1s0 as an upstream interface where the
2853 DHCPv6 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
</para>
2857 <title>A bridge with two enslaved links
</title>
2859 <programlisting># /etc/systemd/network/
25-bridge-static.network
2864 Address=
192.168.0.15/
24
2866 DNS=
192.168.0.1</programlisting>
2868 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
1.network
2873 Bridge=bridge0
</programlisting>
2875 <programlisting># /etc/systemd/network/
25-bridge-slave-interface-
2.network
2880 Bridge=bridge0
</programlisting>
2882 <para>This creates a bridge and attaches devices
<literal>enp2s0
</literal> and
2883 <literal>wlp3s0
</literal> to it. The bridge will have the specified static address
2884 and network assigned, and a default route via the specified gateway will be
2885 added. The specified DNS server will be added to the global list of DNS resolvers.
2893 # /etc/systemd/network/
20-bridge-slave-interface-vlan.network
2909 EgressUntagged=
300-
400</programlisting>
2911 <para>This overrides the configuration specified in the previous example for the
2912 interface
<literal>enp2s0
</literal>, and enables VLAN on that bridge port. VLAN IDs
2913 1-
32,
42,
100-
400 will be allowed. Packets tagged with VLAN IDs
42,
300-
400 will be
2914 untagged when they leave on this interface. Untagged packets which arrive on this
2915 interface will be assigned VLAN ID
42.
</para>
2919 <title>Various tunnels
</title>
2921 <programlisting>/etc/systemd/network/
25-tunnels.network
2932 <programlisting>/etc/systemd/network/
25-tunnel-ipip.netdev
2938 <programlisting>/etc/systemd/network/
25-tunnel-sit.netdev
2944 <programlisting>/etc/systemd/network/
25-tunnel-gre.netdev
2950 <programlisting>/etc/systemd/network/
25-tunnel-vti.netdev
2956 <para>This will bring interface
<literal>ens1
</literal> up and create an IPIP tunnel,
2957 a SIT tunnel, a GRE tunnel, and a VTI tunnel using it.
</para>
2961 <title>A bond device
</title>
2963 <programlisting># /etc/systemd/network/
30-bond1.network
2971 <programlisting># /etc/systemd/network/
30-bond1.netdev
2977 <programlisting># /etc/systemd/network/
30-bond1-dev1.network
2979 MACAddress=
52:
54:
00:e9:
64:
41
2985 <programlisting># /etc/systemd/network/
30-bond1-dev2.network
2987 MACAddress=
52:
54:
00:e9:
64:
42
2993 <para>This will create a bond device
<literal>bond1
</literal> and enslave the two
2994 devices with MAC addresses
52:
54:
00:e9:
64:
41 and
52:
54:
00:e9:
64:
42 to it. IPv6 DHCP
2995 will be used to acquire an address.
</para>
2999 <title>Virtual Routing and Forwarding (VRF)
</title>
3000 <para>Add the
<literal>bond1
</literal> interface to the VRF master interface
3001 <literal>vrf1
</literal>. This will redirect routes generated on this interface to be
3002 within the routing table defined during VRF creation. For kernels before
4.8 traffic
3003 won't be redirected towards the VRFs routing table unless specific ip-rules are added.
3005 <programlisting># /etc/systemd/network/
25-vrf.network
3015 <title>MacVTap
</title>
3016 <para>This brings up a network interface
<literal>macvtap-test
</literal>
3017 and attaches it to
<literal>enp0s25
</literal>.
</para>
3018 <programlisting># /usr/lib/systemd/network/
25-macvtap.network
3023 MACVTAP=macvtap-test
3028 <title>A Xfrm interface with physical underlying device.
</title>
3030 <programlisting># /etc/systemd/network/
27-xfrm.netdev
3035 InterfaceId=
7</programlisting>
3037 <programlisting># /etc/systemd/network/
27-eth0.network
3042 Xfrm=xfrm0
</programlisting>
3044 <para>This creates a
<literal>xfrm0
</literal> interface and binds it to the
<literal>eth0
</literal> device.
3045 This allows hardware based ipsec offloading to the
<literal>eth0
</literal> nic.
3046 If offloading is not needed, xfrm interfaces can be assigned to the
<literal>lo
</literal> device.
3052 <title>See Also
</title>
3054 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
3055 <citerefentry><refentrytitle>systemd-networkd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
3056 <citerefentry><refentrytitle>systemd.link
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
3057 <citerefentry><refentrytitle>systemd.netdev
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
3058 <citerefentry><refentrytitle>systemd-resolved.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>